Usually asphalt around the edges of the grate begin to deteriorate over time due to vibration from traffic and from expansion and retraction during hot and cold weather and rain.
This break up process is accelerated in the winter months when water in the crack freezes and expands and the pressure enlarges the gap into a crack etc.
Even a small hole will eventually become a big hole
and expose the steel edge of the grate to traffic. Filling the hole with asphalt is a temporary fix, but within a short time the process will start over again probably even quicker than originally.
The reason is that the new material does not bond well with the older material and within a short time water enters the minute gap between the two materials and with the force of tires passing over, the water becomes a jet of water, thus opening the gap further.
There are many fixes, but of course we recommend 4Seasons™ Pourable Pothole Filler, which is a liquid, rubberized, pourable filler used to fill cracks, potholes, and irregularities in asphalt & concrete pavement.
The photo on above, shows the grate after application of 4Seasons™ and a photo on the right, taken five years later shows the repair still as good as new.
Visit http://liquidpotholefiller.com